Pump



Jan. 21, 1969 o. LUTZ 3,422,749

Filed June 19, 1967 Sheet of 2 United States Patent L 53,875 US. Cl. 103-130 7 Claims Int. Cl. F04c 1/00; F04c /00 ABSTRACT OF THE DISCLOSURE A pump having a pump chamber of approximately equilateral polygonal configuration in cross-section and having at least four corners, a crankshaft journalled in the pump casing, the crankpin of the crankshaft being mounted in the pump chamber and having circular crank webs to form at least a part of the front end of the pump chamber, resilient diaphragms extending along the width of the pump chamber, each diaphragm being firmly clamped with one edge in a corner of the pump chamber and supported with a flat side on the crankpin, inlet and outlet slots in the crank webs cooperating with peripherically distributed suction ports and outlet orifices in the walls of the pump casing covered by the crank webs.

This invention relates to a pump for gases and liquids. Rotary pumps for liquids and gases are known which have a cylindrical casing with an eccentrically mounted rotor journalled therein. The rotor carries in radial slots blades or plates which are urged against the internal wall of the cylindrical casing by means of springs or centrifugal force to form cells on rotation of the rotor, said cells continuously increasing (sucking) and decreasing (pressing) to deliver the liquid or gas from the suction side to the pressure side. The number of said blades is at least four.

Pumps of this type have the disadvantage that the blades have to be mounted most exactly and that the blades have a high relative speed with respect to the rotor and a tendency to flutter.

It is an object of the invention to provide a pump which is most simple in structure, and in operating is subject but to low wear. Furthermore, the pump is to operate with a simple slot control.

According to the invention such a pump comprises a pump chamber of approximately equilateral polygonal configuration in a cross-section with at least four corners, a crankshaft journalled in the pump casing, the crankpin of said crankshaft being mounted in the pump chamber, the latter having circular crank webs forming at least a part of the front end of the pump chamber, resilient diaphragms extending along the width of the pump chamber, each diaphragm being secured with one edge in the corner of the pump chamber and supported with a flat side on said crankpin, inlet and outlet slots in the crank webs cooperating with peripherically distributed suction ports and outlet orifices in the end walls of the pump casing covered by the crank webs.

The friction between the crankpin and the diaphragms may be reduced by a freely rotatable sleeve mounted on said crankpin.

The inlet and outlet slots may be arranged in a single crank web on various radii.

Other features and advantages are described hereinafter with reference to the drawings, wherein FIG. 1 is a vertical section through a pump according to the invention along the line II as shown in FIG. 2.

FIG. 2 is a view along the line 11-11 as shown in FIG. 1.

FIG. 3 is a partial view of the left hand part of the 'ice pump shown in FIG. 1 with control slots in a crank web.

FIG. 4 is a plan view of the crank web of the embodiment shown in FIG. 3 viewed in the direction of arrow A.

FIG. 5 shows a cross-section of a modified embodiment of the pump chamber.

The pump as shown in FIGS. 1 and 2 has a casing 2 provided with flanges 4 on both ends thereof. Both ends of the casing 2 are provided with end covers 6, 8 wherein a crankshaft 14 is journalled in bearings 10, 12. The crankpin 16, which has an eccentricity 2, extends along the entire length of the pump chamber 18. Furthermore, the crankshaft 14 has crank webs 20, 22 of circular circumference at both ends of the crankpin which form at least the major part of the end walls of the pump chamber and are concentric with the axis of the bearings 10, 12. The crank webs 20 and 22 are fitted in circular recesses 24, 26 provided in the casing covers 6 and 8.

As will be seen from FIG. 2 the pump chamber 18 is of approximately equilateral quadrangular structure in cross-section. Resilient diaphrgams over blades 28, 30, 32 and 34 are secured along one edge in suitably formed slots in the corners of the pump chamber, the length of said diaphragms corresponding with about the length of the lateral edges of the pump chamber. As shown in FIG. 2 said diaphragms 28 through 34 bear against a sleeve 38 rotatably mounted on the crankpin 14 by means of a bearing 36. The width of the diaphragms corresponds to the width of the pump chamber between the crank webs 20, 22 with a minimum clearance.

The crank webs are provided with inlet and outlet slots, each being arranged in staggered relationship by approximately with respect to the crankpin 16.

In the embodiment as shown in FIG. 1 the inlet slot 39 is provided in the crank web 20. An annular groove 40 is provided in the casing cover 6 on the same radius as the inlet slot; this annular groove 40 may, in case of the pump being used as an air compression pump, communicate with the environment through bores 42. The outlet slot 44 is provided in the opposite crank web 22, said outlet slot cooperating with an annular groove 46 provided in the casing cover 8 and communicating with a connecting piece 43 adapted to be connected to a pipe or hose.

The pump is driven through the crankshaft journal 50. The crankshaft rotates in the direction of arrow. In rotating the volume of each of the chambers or cells I through IV confined by the diaphragms 28 through 34 and the walls of the pump chamber is increased or decreased, the increasing chambers taking in, whilst the medium in the decreasing cells is compressed.

In order to keep the bending stress of the diaphragms 28 through 34 low the areas of the casing walls adjacent the clamping points are of a radius 52 adapted to limit the bending deformation and thus the stress of the diaphragms. To reduce the bending stress the diaphragms may consist of a plurality of individual diaphragm members stacked one upon another, whereby at the same time a damping is achieved by the interlaminar friction between said diaphragms.

In the embodiment according to FIG. 3 the inlet slot 39 and the outlet slot 44 are arranged in the same crank web, the two slots being arranged at different radii a and b. An annular groove 40 is provided in the casing cover 8 opposite the inlet slot 39, whilst an annular groove 46 is arranged opposite the outlet slot, the annular grooves being sealed against each other by an annular sealing member 54 bearing against the crank web 22. The annular groove 40 communicates with the environment through bores 42, whilst the annular groove 46 is connected with a connecting piece 48 through bores 56.

As will be seen from FIG. 4 this embodiment shows the outlet slot arranged in staggered relationship with respect to the axis of the crankpin 16 by an angle greater than 90, this being due to the asymmetry of the individual pump cells on the different radii.

As regards the position of the inlet and outlet slots it may be said in general that these are arranged so as to be each positioned in the opposite cells which on rotation of the crankpin 16 are of about equal size. The

proper arrangement and construction of the inlet and outlet slots may be exactly defined for each compression ratio. With a compression ratio of l the pum is able to deliver also liquids.

In the modified embodiment as shown in FIG. 5 the walls of the pump chamber 18 have surfaces 58 which are nearly at right angle with respect to the wall surfaces, the ends of the diaphragms sweeping past said surfaces 58 at a short distance at the end of their track of travel.

As will further be seen from FIG. 5 the crankshaft may be provided with a continuous axle 60 on which an eccentric 62 forming the crankpin is mounted; the mass of said eccentric may be reduced by a relief bore 64.

According to the foregoing the pump is described and illustrated with embodiments having four diaphragms, but it is of course possible to use a greater number of diaphragms.

Preferably the diaphragms are made of spring steel, but diaphragms made of graphitic carbon may be used as well.

The sleeve may also be of graphite or another material low in friction, such as polytetrafluoro ethylene (PTFE). The diaphragms may be coated with a thin coating of PTFE on the side adjacent the crankpin.

It is further possible to provide the crankshaft to be mounted in a bearing on one end only, general modifications With respect to specific structural features being possible as well without departing from the scope and spirit of the invention.

I claim:

1. A pump comprising a pump chamber of approximately equilateral polygonal configuration in cross-section and having at least four corners, a crankshaft journalled in the pump casing, the crankpin of said crankshaft being mounted in the pump chamber and having circular crank webs to form at least a part of the front end of said pump chamber, resilient diaphragms extending along the width of said pump chamber, each diaphragm being firmly clamped with one edge in a corner of said pump chamber and supported with a flat side on said crankpin, inlet and outlet slots in said crank webs cooperating with peripherically distributed suction ports and outlet orifices in the end walls of the pumpcasing covered by said crank webs.

2. A pump claimed in claim 1, comprising a freely rotatable sleeve mounted on said crankpin.

3. A pump as claimed in claim 1, wherein the inlet and outlet slots are provided in a crank web at different radii.

4. A pump as claimed in claim 1, comprising annular grooves provided on the side of the end walls of the pump casing adjacent said crank web, said annular grooves being arranged on the same radius as the inlet and outlet slots.

5. A pump as claimed in claim 1, wherein clamping slots are provided in the corners of the pump chamber for the diaphragms.

6. A pump as claimed in claim 1, wherein the wall sections adjacent the clamping points for the diaphragms are provided with a radius.

7. A pump as claimed in claim 1, wherein each diaphragm comprises a plurality of laminated thin diaphragm members.

References Cited UNITED STATES PATENTS 658,556 9/1900 Pitt 91-56 1,660,183 2/1928 Weeden 103-124 1,734,433 11/ 1929 Hoyt. 1,864,699 6/1932 Varley 103130 2,938,505 5/1960 Quartier 911 18 3,224,421 12/1965 Peras 23 0145 3,282,496 11/1966 Radziwill et al 230149 FOREIGN PATENTS 292,714 6/1916 Germany.

FRED C. MATTERN, JR., Primary Examiner.

W. I. GOODLIN, Assistant Examiner.

US. Cl. X.R. 

